Mechanical shaping

ABSTRACT

A method of mechanically shaping a metallic object, which comprises the steps of, coating a metallic object with a ductile, polyvinyl acetate and/or polyvinyl alcohol, non-metallic polymer base material having a maximum thickness of 0.1 mil, and increasing the length of the coated metallic object while simultaneously reducing its cross-sectional area with a former which substantially surrounds its perimeter.

Beigay et al.

[ MECHANICAL SHAPING [75] Inventors: Jack M. Beigay, Freeport; Edward G.Choby, Jr., Pittsburgh, both of Pa.; Joseph S. Kaferle, Ashtabula, vOhio [73] Assignee: Allegheny Ludlum Industries, Inc.,

Pittsburgh, Pa.

[22] Filed: Mar. 10, 1972 [21] Appl. No.: 233,783

Related U.S. Application Data [63] Continuation-in-part of Ser. No.25,589, April 3,

1970, abandoned.

[52] U.S. Cl. 72/46 [51] Int. Cl. B2lc 3/14, B2lc 23/24, B2lj 3/00 [58]Field of Search...252/l2, 12.2, 12.4, 12.6, 252/52 R, 56 S; 72/4l,42,43,46,47, 286, 289

[ 56] References Cited UNITED STATES PATENTS Clappier et a1. 252/12 Jan.29, 1974 3,453,208 7/1969 Gallagher et al. 252/12 2,135,659 1 H1938Elfstrom 72/43 2,346,124 4/1944 Dew 252/52 R 3,031,749 5/1962 Adams252/52 R FOREIGN PATENTS OR APPLICATIONS 1,004,836 9/1965 Great Britain72/46 Primary Examiner-Charles W. Lanham Assistant Examiner-E. M. CombsAttorney, Agent, or Firm-Vincent G. Giola [5 7] ABSTRACT A method ofmechanically shaping a metallic object, which comprises the steps of,coating a metallic object with a ductile, polyvinyl acetate and/orpolyvinyl alcohol, non-metallic polymer base material having a maximumthickness of 0.1 mil, and increasing the length of the coated metallicobject while simultaneously reducing its cross-sectional area with aformer which substantially surrounds its perimeter.

18 Claims, No Drawings MECHANICAL SHAPING This application is acontinuation-in-part of now abandoned copending application Ser. No.25,589 filed April 3, 1970.

The present invention relates to an improved method for mechanicallyshaping an object and more particularly to an improved method formechanically shaping a metallic object.

Copper plating has been applied to carbon steel golf shafts prior tomechanical shaping. It provides a coating which furnishes the steel withprotection against scratching and marking and provides the steel with asurface which holds, retains, and carries lubricants into closetolerance formers, i.e., mechanical shapers.

A similar use of copper plating on stainless steel golf shafts has not,however, proved to be desirable. The adhesion of copper onto stainlesssteel is not as dependable or as strong as is the adhesion of copperonto carbon steel. Copper plated stainless steel often results in theneed for replating or in the flaking off of copper during shaping.

With the use of copper plating on stainless steel golf shafts all butruled out, there arose a need for a protective coating which could beused in those mechanical shaping operations wherein a metallic object,e.g., a golf shaft, is passed through a former which substantiallyreduces the cross-sectional area of the object. The coating had tofurnish the stainless steel with protection against scratching andmarking and had to provide the steel with a surface which holds,retains, and

carries lubricants. y

We have found that polyvinyl acetate and polyvinyl alcohol, non-metallicpolymer base coatings, having a maximum thickness of 0.1 mil, can beused on stainless steel golf shafts and other metallic objects toprovide the protection that copper plate furnishes carbon steel golfshafts. Coatings of this general nature have been used for protection ofsurfaces which undergo normal handlingand long-time storage, but havenot been successfully used in mechanical shaping operations wherein ametallic object is placed between or passed through a former whichsubstantially surrounds its perimeter. Mechanical shaping operations ofthis nature produce sizeable reductions in area and subject an object toa type'of treatment which is not encountered during normal handling andeven during other forms of mechanical shaping, such as rolling and deepdrawing. Rolling and deep drawing do not place the entire perimeter ofthe object being shaped in compression as does a former when-an objectis placed between or passed through it. Furthermore, formers whichsubstantially surround the perimeter are prone to defects which scratchthe object being formed and cannot be flooded with lubricants, as areroll formers.

British Patent Specification No. 1,004,836 discloses the use ofpolyvinyl acetate on metal surfaces which are being drawn, but statesthat polyvinyl acetate is a decidedly inferior coating, and the worstcoating in a group of poor coatings. Significantly, the polyvinylacetate was applied in a thickness of 0.35 mil whereas the maximumthickness of the present invention is 0.1 mil.

Still, an additional advantage which is not obtained from the use ofcopper plate is realized from the use of non-metallic polymer basecoatings, when the shaped object is subsequently heat treated. Coppermust be chemically or electrochemically stripped from the mechanicallyshaped objects prior to heat treatment. The non-metallic polymer basecoatings, however, do not have to be removed. They can be left on theshaped object and are useful in reducing the amount of scale formedduring heat treatment. This in turn minimizes the pickling which must beperformed to remove scale and reduce the criticalities involved inpickling golf shafts and other objects which require close control ofweight loss.

Use of the non-metallic polymer base coatings have still furtheradvantages. First of all, the life of the former is increased as metalto .metal contact is avoided. Secondly, the coatings can be left on theshaped object to provide protection during subsequent fabricatingoperations, e.g., wire coiling.

It is accordingly an object of this invention to provide an improvedmethod of mechanically shaping a metallic object.

It is another object of this invention to provide an improved method ofmechanically shaping and heat treating a metallic object.

It is a further object of this invention to provide an improved methodof mechanically shaping and fabricating a metallic object.

The method of the present invention comprises the steps of coating ametallic object with a ductile, polyvinyl acetate and/or polyvinylalcohol, non-metallic polymer base material which has a greateradherence to the metallic object than to itself and which has a surfacewhich holds, retains, and carries lubricants into close toleranceformers, and increasing the length of the coated metallic object whilesimultaneously reducing its cross-sectional area with a former whichsubstan tially surrounds its perimeter. The coating must be ductilesince the mechanically shaped article has more surface area aftershaping than before, must have 'a greater adherence to the metallicobject than to itself, i.e., it

should crack before peeling, so that it will exhibit strong anddependable adhesion, and must have a surface which holds, retains, andcarries lubricant through close tolerance formers, (numerous coatingswould be wiped clean of lubricant upon entrance into a die) so as tofacilitate shaping. The mechanical shaping operation could be drawing,pressing, extrusion swaging or any other operations which encompassesthe placing between or passing of a metallic object through a former. Itgenerally causes a reduction in area of at least 20 percent, i.e., thecross-sectional area of the shaped objectis generally less than percentof the original cross-sectional area, from one or more passes throughthe former.

In certain instances the method encompasses a heat treating operationsubsequent to shaping, e.g., stainless steel golf shafts are annealedand age hardened. Use of non-metallic polymer base materials isparticularly desirable in these instances as they reduce the amount ofscale formed during heat treating and in turn minimize pickling. Asdiscussed above, this reduction in pickling is highly advantageous forthe manufacture of golf shafts and other objects which require a controlof weight loss. It should, however, be noted that it is often desirableto remove the lubricant from the coating by vapor degreasing or othertreatment prior to heat treatment as many lubricants will soften thecoating, thereby, reducing its effectiveness.

In other instances the method encompasses additional fabricatingoperations subsequent to the, hereinbefore, described mechanical shapingoperation in which the cross-sectional area of the object is reduced.These operations include coiling processes in which previously drawnstainless steel wire is wound into a spring by means of a coiling tool.During coiling the non-metallic polymer base coating protects thestainless steel from damage caused by coiling tools which wouldotherwise scratch and roughen the surface of the steel and, therebydecrease its corrosion resistance.

The method of this invention is believed to be applicable to a widevariety of metals and objects which can have various forms. Emphasis hasbeen placed upon stainless steel as it is probably the most importantdecorative metal and one of the few that will retain its brilliantsurface through the years. The only restriction placed upon the form ofthe metal object is that it be suitable for the particular shapingoperations embraced by this invention. Wire, rods, tubes and bars aretypical forms. Tubes are generally reduced with the aid of a mandrel toinsure constant wall thickness.

Any of the well-known coating methods can be employed. The invnetion isnot dependent upon the use of any particular coating method.Illustrative coating methods are dip coating, flow coating, spraycoating, and roll coating.

The preferred coating solution which satisfies the requirements of thisinvention is an aqueous of polyvinyl acetate. The solution shouldcontain at least 1 percent by weight, polyvinyl acetate to insure acoating of adequate thickness and preferably should contain at least 3percent. An upper preferred limit of percent, by weight, polyvinylacetate is imposed as thicker coatings to not adhere as tenaciously asdo thinner coatings and since thicker coatings are more difficult toremove. Solutions with more than 15 percent polyvinyl acetate are,however, within the scope of the invention as long as they do not yielda coating greater than 0.1 mil thick. Coatings thicker than 0.1 ofa milproduce an excessive degree of chatter during mechanical shaping.Chatter is defined as vibrations of the former or workpiece whichproduce a wavy surface on the object being formed. Although we do notknow for sure why coatings thicker than 0.1 mil affect the degree ofchatter, we hypothesize that the use of thicker coatings results in acoating build-up at the entrance of the former and this in turn causesan irregular movement of the workpiece through the former. As statedabove, the coatings of this invention have a greater adherence to themetallic object than to themselves and, moreover, thicker coatings donot adhere as tenaciously as do thinner coatings.

Polyvinyl alcohols are additional coating solutions which satisfy therequirements of this invention. They can be obtained by thetransesterification of polyvinyl acetate with methyl alcohol under theaction of acid or base catalysis. Methyl acetate is removed from thereaction mixture as a by-product. The polyvinyl alcohols can containacetate groups which have not been transformed. Mixed polyvinylalcohol-acetate resins will have properties intermediate betweenpolyvinyl acetate and polyvinyl alcohol.

A wetting agent can be added to the coating solution to insure the bestpossible wetting action at the metal surface. The use of wetting agentsis optional and by no means necessary. A fatty acid amino type of soaphas been successfully used with aqueous solutions of polyvinyl acetatein ranges varying between 10-20 percent, by weight, of the total solidswithin the solution.

The following examples emphasize several aspects of the invention.

EXAMPLE I A group of stainless steel golf shafts were dip coated in anaqueous solution of polyvinyl acetate which had a fatty amino type ofsoap present as an emulsifier. The solids were approximately 7.5 percentby weight of the aqueous solution. A second group of golf shafts weredip coated in another aqueous solution of polyvinyl acetate which alsohad a fatty acid amino type of soap present as an emulsifier. The solidspresent in this solution were approximately 5.55 percent by weight ofthe aqueous solution. Both groups of golf shafts were step tapered in ahydraulic press, age hardened at 900 F for 8 hours and subsequentlypickled.

The shafts were substantially free from scratches and marks and were ofthe proper weight.

EXAMPLE 11 Coating Thickness (mils):

Size

0.089 0.079 0.072 0.065 0.058 0.052 0.047 0.043 0.038 0.034 0.032 TotaluuNwuA-NOMM N OO-NLnu-MMONN aolouuNu-ioovioo aooosnuooooocfooooooooooooThe test results stress the criticality of a maximum coating thicknessof 0.1 mil. They show that chatter is virtually eliminated with acoating of 0.067 mil and eliminated for all practical purposes with acoating of 0.l mil, and that chatter significantly increases withcoating thicknesses in excess of 0.1 mil.

It will be apparent to those skilled in the art that the novelprinciples of the invention disclosed herein in connection with specificexamples thereof, will suggest various other modifications andapplications of the same. It is accordingly desired that in construingthe breadth of the appended claims they shall not be limited to thespecific examples of the invention disclosed herein.

We claim:

1. An improved method of mechanically shaping a metallic object, whichcomprises the steps of: coating said metallic object with a ductile,non-metallic polymer base material from the group consisting ofpolyvinyl acetate solutions, polyvinyl alcohol solutions and mixturesthereof, said polymer base material having a greater adherence to saidmetallic object than to itself and having a surface which holds,retains, and carries lubricants into close tolerance formers, saidcoating having a maximum thickness of 0.1 mil; and increasing the lengthof said coated metallic object while simultaneously reducing itscross-sectional area with a former which substantially surrounds itsperimeter.

2. A method according to claim 1 wherein the step of increasing thelength of said coated metallic object while simultaneously reducing itscross-sectional area comprises the step of drawing said object throughsaid former.

3. A method according to claim 1 wherein the step of increasing thelength of said coated metallic object while simultaneously reducing itscross-sectional area comprises the step of extruding said object throughsaid former.

4. A method according to claim 1 wherein the step of increasing thelength of said coated metallic object while simultaneously reducing itscross-sectional area comprises the step of pressing said object withsaid former.

5. A method according to claim 1 wherein the step of increasing thelength of said coated metallic object while simultaneously reducing itscross-sectional area comprises the step of swaging said object with saidformer.

6. A method according to claim 1 wherein said metal lic object is astainless steel object.

7. A method according to claim 1 wherein said metallic object has asubstantially circular perimeter.

8. A method according to claim 1 wherein the crosssectional area of saidmetallic object is reduced at least percent by said former.

9. A method according to claim 1 including the steps of heat treatingsaid coated and mechanically shaped metallic object and subsequentlyremoving said coating therefrom.

10. A method according to claim 9 including the step of removinglubricant from the mechanically shaped object prior to heat treating.

11. A method according to claim 1 wherein said nonmetallic polymer basematerial is an aqueous solution of polyvinly acetate.

12. A method according to claim 11 wherein said aqueous solution ofpolyvinyl acetate contains at least about 1 percent by weight polyvinylacetate.

13. A method according to claim 12 wherein said aqueous solution ofpolyvinyl acetate contains from about 3 percent to about 15 percent byweight polyvinyl acetate.

14. A method according to claim 13 wherein said aqueous solution ofpolyvinyl acetate contains a wetting agent.

15. A method according to claim 14 wherein said wetting agent is a fattyacid amino type of soap.

16. A method according to claim 1 wherein said nonmetallic polymer basematerial is a polyvinyl alcohol.

17. A method according to claim 7 wherein said metallic object is a rod,wherein the step of increasing the length of said coated metallic objectwhile simulta neously reducing its cross-sectional area comprises thestep of drawing said rod into wire, and including the step of coilingsaid wire.

18. A method according to claim 17 wherein said metallic object is astainless steel rod.

2. A method according to claim 1 wherein the step of increasing thelength of said coated metallic object while simultaneously reducing itscross-sectional area comprises the step of drawing said object throughsaid former.
 3. A method according to claim 1 wherein the step ofincreasing the length of said coated metallic object whilesimultaneously reducing its cross-sectional area comprises the step ofextruding said object through said former.
 4. A method according toclaim 1 wherein the step of increasing the length of said coatedmetallic object while simultaneously reducing its cross-sectional areacomprises the step of pressing said object with said former.
 5. A methodaccording to claim 1 wherein the step of increasing the length of saidcoated metallic object while simultaneously reducing its cross-sEctionalarea comprises the step of swaging said object with said former.
 6. Amethod according to claim 1 wherein said metallic object is a stainlesssteel object.
 7. A method according to claim 1 wherein said metallicobject has a substantially circular perimeter.
 8. A method according toclaim 1 wherein the cross-sectional area of said metallic object isreduced at least 20 percent by said former.
 9. A method according toclaim 1 including the steps of heat treating said coated andmechanically shaped metallic object and subsequently removing saidcoating therefrom.
 10. A method according to claim 9 including the stepof removing lubricant from the mechanically shaped object prior to heattreating.
 11. A method according to claim 1 wherein said non-metallicpolymer base material is an aqueous solution of polyvinly acetate.
 12. Amethod according to claim 11 wherein said aqueous solution of polyvinylacetate contains at least about 1 percent by weight polyvinyl acetate.13. A method according to claim 12 wherein said aqueous solution ofpolyvinyl acetate contains from about 3 percent to about 15 percent byweight polyvinyl acetate.
 14. A method according to claim 13 whereinsaid aqueous solution of polyvinyl acetate contains a wetting agent. 15.A method according to claim 14 wherein said wetting agent is a fattyacid amino type of soap.
 16. A method according to claim 1 wherein saidnon-metallic polymer base material is a polyvinyl alcohol.
 17. A methodaccording to claim 7 wherein said metallic object is a rod, wherein thestep of increasing the length of said coated metallic object whilesimultaneously reducing its cross-sectional area comprises the step ofdrawing said rod into wire, and including the step of coiling said wire.18. A method according to claim 17 wherein said metallic object is astainless steel rod.